NEW YORK — For 94-year-old Canadian Olga Kotelko, it’s not the high jump, javelin throw, pole vault or sprint that poses the biggest fitness challenge. It’s finding someone age-appropriate to compete against.

Kotelko, a Vancouver-based retired schoolteacher, took up track and field at age 77. She has a closet full of medals, but with so few other women athletes in her age bracket, she often finds herself competing against 80-to 85-year-olds, or men.

“I love competing against athletes my own age but if I don’t have any, I’ll compete against myself,” said Kotelko, who sprints, throws and jumps in 11 track and field events.

Kotelko defies the standard image of aging and typefies what scientists call compression of morbidity. She has managed to postpone the onset of chronic or debilitating illness and is still going strong.

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Born on a farm in Saskatchewan, Kotelko played softball in her youth, but did not take up another sport until after retirement, when she became addicted to track and field.

To keep her edge, she works out for at least an hour and a half every day. She takes a water aerobics class three times a week, and regularly does stretching exercises, deep breathing, and reflexology for her hands and feet.

“I’ll end up with splits,” said Kotelko, who often hits the exercise mat in the middle of a sleepless night.

Canadian author Bruce Grierson lives near Kotelko. While bedeviled by his own midlife aches and pains, he was so astonished by her feats that he persuaded her to allow scientists to study her in hopes of uncovering her secret to aging well.

His recent book “What Makes Olga Run” chronicles her story and the test results.

“She was curious about her own physiology, so she agreed to be a bit of an open book,” Grierson, 51, said.

The results of the scientific studies at The Beckman Institute in Urbana, Illinois, which did a battery of MRIs and memory and cognitive tests on Kotelko, show that her health and prowess are mainly due to a combination of good habits, a positive attitude, and her naturally driven personality.

“It’s impossible to tease out what’s driving the bus,” he said, “But genes aren’t the half of it with Olga. It’s the way she has lived her life.”

Tests showed that, by some measures, Kotelko has the brain of a 50- or 60-year-old, according to Grierson. Often the gap between brain and skull grows with aging but Kotelko’s resembles that of a much younger person.

Her hippocampus, a small region of the brain associated with memory and spatial navigation that is known to respond well to exercise, looks especially good.

But Grierson said she showed signs of aging in other areas, and despite Kotelko’s abilities, she finds it difficult to learn new techniques.

McGill University in Montreal conducted physiological tests that are ongoing. Scientists there are preparing to analyze her blood to see if anything about it could explain her vigor.

Kotelko said she avoids injury by keeping her body tuned up, not training when it rains, and eating four or five small meals a day.

“She’s very attuned to what her body is telling her. She doesn’t get overstressed,” Grierson said.

“Her high jump may not be super high, but she still springs off the ground with good technique,” he explained. “She’s rare. It’s called compression of mortality: You go great guns till almost the very end.”

Dr. Robert E. Sallis, a physician with the American College of Sports Medicine, explained it as squaring off the geriatric curve that plots functional capacity, versus age.

“People who are inactive tend to lose functional capacity much earlier than those who are active,” Sallis said.

But those who remain active and fit can maintain a high functional capacity, often almost until they die.

“So you see a squaring of their geriatric curve and a high functional capacity right up until the end,” he said.